Commutator and modulator



y 1960 J. MATARESE 2,935,647

COMMUTATOR AND MODULATOR Filed Feb. 11, 1958 2 Sheets-Sheet 2 INPUT PUSH-PULL SIGNAL I/VPI/T J'IGNAL INVENTOR JU/M/ M4 TARESE BY q + w ATI'QRNEY electrodes.

- 2,935,647 I COMMUTATOB AND MODULATOR- JohnMatarese, Bronx, N.Y., assignon hy niesne assigna I ments, to Sylvania Electric Products Inc., Wilmington,

Del., a corporation of Delaware Application February 11, 1958, Serial No. 714,625

8 Claims. (Cl. 315-169) My invention is directed toward electroluminescen image display devices.

Certain types of phosphors, known to the artas electroluminescent phosphors, will luminesce under the infiuence of an externally applied electric field, the intensity of the emitted light being a function of the strength of this applied field. Such phosphors can be dispersed in dielectric media to form electroluminescent films orlayers, which constitute transducers for transforming electrical energy to light energy.

It is known that when an electroluminescent layer of this type is interposed and electrically coupled between two arrays, of parallel, separated, electrical conductors, the conductors of one array being perpendicular to the conductors of the other array, a crossed-grid structure is formed wherein a portion of the film (defined as a cell) is connected between one horizontal conductor and one 7 vertical conductor. When a suitable voltage is applied between any one horizontal-vertical conductor pair, the cell connected between this pair will luminesce to a degree dependent upon the magnitude of this voltage.

Further, it has been proposed to switch or commutate these applied voltages in such manner as to successively energize each cell in turn, thus producing an effect analogous to cathode ray tube scanning.

It is an object of the present invention to improve apparatus for applying commutating voltages and modulating voltages simultaneously to a crossed-grid structure.

Another object is to utilize a circuit employing a plurality of rectifiers and beam switching tubes in applying commutating and modulating voltages simultaneously to a crossed-grid structure.

Still another object is to provide new and improved apparatus for the successive commutation and modulation of all cells in a crossed-grid structure.

These and other objects of the invention will either be explained or will become apparent hereinatfer.

In accordance with the principles of my invention, I

layer formed from a dispersion of electroluminescent phosphors in dielectric media interposed between and electrically coupled to the conductors of both arrays.

I further provide first and second switching tubes, each tube being associated with the conductors of the corresponding array. Each tube includes a plurality of output electrodes (which can be either anodes or cathodes) equal to the number of conductors in the corresponding array, a single input electrode (which can be either a cathode or an anode), and a plurality of switch are coupled together.

In addition, I provide a first set of rectifiers (all poled in the same sense), each rectifier being coupled between Each output electrode is coupled to its corresponding conductor. The input electrodes of both tubes .a first common terminal and a corresponding output elec- 2,935,647, Patented May 3, 1960 2 trode of the first tube. Similarly, a second set of rectifiers (all poled in the same sense) are each coupled between a second common terminal and a corresponding output electrode ofthe second tube.

When appropriate operating potentials are applied between the output and input electrodes of each tube, and

the switching electrodes of the tubes are properly energized each cell in the cross-grid structure will be sequentially conditioned for operation in turn. Thus, the requisite commutation action is obtained.

When both tubes are of'the same type, i.e. the output electrodes of both tubes are all either anodes or cathodes and the input electrodes of both tubes are all either cathodes or anodes, then the rectifiers in both rectifier sets are all poled in the same sense; Modulation is then accomplished by means of two phase opposed input signals. More particularly, first and secondinput signals, opposed in :phase but otherwise identical,are respectively supplied to the first and second terminals. During the interval in which any one cell is conditioned for operation by the commutation action previously described, the first and second signals are applied to the corresponding first array and second array conductors associated with this cell.

As a result, the light ouput from each cell, when conditioned for operation, is modulated, the light emitted Varying in accordance with a voltage equal to the algebraic difference between the instantaneous amplitudes of the first and second signals.

The switching tubes can be of different types, i.e. the output electrodes of the first tube are anodes while the output electrodes of the second tube are cathodes, the input electrode of the first tube being a cathode, the in put electrode of the second tube being an anode.

Under these circumstances, the rectifiers in the first set are poled in opposite sense to the rectifiers of the second set. Moreover, the first and second common terminals are coupled together, and a single alternating signal is supplied thereto. However, the light ouput from each cell, when conditioned for operation, is again modulated in substantially the same manner as above.

Illustrative embodiments of my invention will now be described in more detail with reference to the accompanying drawings wherein Fig. 1 is a circuit diagram of one embodiment of my invention;

Figs. 2 and 3 show auxiliary apparatus employed in conjunction with the circuit of Fig.1;

Fig. 4 is a circuit diagram of a second embodiment of my invention; and

Fig. 5 is a circuit diagram of a third embodiment of my invention.

Referring now to Fig. 1, there is shown a crossed-grid structure provided with a first array of horizontal electrical conductors 42, 44 and 46 and a second array of vertical electrical conductors 64, 66 and 68, with an electroluminescent layer (not shown) interposed between and electrically coupled between the conductors of both arrays.

Each of horizontal conductors 42, 44 and 46 is coupled through a corresponding one of rectifiers 36, 38 and 40 to a first terminal 22. Each of the vertical conductors is coupled through a corresponding one of rectifiers 58, 60 and 62 to a second terminal 24. All rectifiers are poled in the same sense.

A first switching tube 26 contains, within an evacuated or gas filled envelope, a plurality of anodes 3t 32 and 34, a single cathode 28, and a plurality of switching electrodes 70 and 72. Anodes 30, 3.2 and 34 are each coupled through a resistor to a point of fixed high positive poten- 'tial and in addition, each of these anodes 30, 32 and '34 is coupled to a corresponding one of horizontal conductors 46, 44 and 42. Cathode 28 is grounded.

g'tiou, each of these anodes 52-, 54 and 56 is coupled to a corresponding one of vertical conductors '46, 44. and- 42. Cathode 50 is grounded.

As shown in Figs. 2 and 3, the switching electrodes 76 and 72 of tube 26 are coupled to corresponding output terminals of a flip-flop 80, vertical control pulses being supplied to the input of flip-flop 80. Similarly, the

switching electrodes 74 and 76 of tube 43 are coupled to corresponding output terminals of a flip-flop 32, horizontal control pulses being supplied to the input of flip-flop 82.

Initially, a conductive path is established, for example,.

between cathode 28 and anode 30 of tube 26. Similarly, a conductive path is established between cathode 50 and anode 52'of tube 48. Anodes 30 and 52 arethus at a low positive direct potential while the other anodes of both tubes, anodes 32, 34, 54 and 56, are at a high fixed direct potential. (Since the electroluminescent layer is formed from electroluminescent phosphor particles dispersed in a dielectric, it responds only to alternating voltages and does not respond to this direct potential.)

The conductive path in each tube can be switched from anode to anode by applying a suitable switching signal directly to the switching electrodes of tubes 26 and 48. Alternatively, as shown in this example, the conductive path in each tube is switched from anode to adjacent anode under the action of a corresponding fiip-flop coupled to the switching electrodes of the tube and responsive to incoming pulses. Hence, in this example, horizontal control pulses are supplied to the input of flip-flop 80, its output being coupled to the switching electrodes 70 and 72 of tube 26. Similarly, vertical control pulses are supplied to the input of flip-flop 82, its output being coupled to the switching electrodes 74 and 76 of tube 48.

This process continues until a conductive path is established between the last anode and the cathode. At this point, the entire switching process repeats itself.

As a result, at any one instant, a selected vertical conductor, for example 64, and a selected horizontal conductor, for example 42, will be at a low potential only slightly more positive than ground potential, while all other conductors are at a high potential. The cell defined by these selected conductors is then conditioned for operation.

A first signal which in this example is an amplitude modulated alternating signal between terminals 22 and 20, while a second signal opposed in phase to the first signal but otherwise identical thereto is applied between terminals 24 and 20. The amplitude of both signals can vary in any manner desired as long as its extreme values, i.e. its maximum and minimum values fall within fixed limits. More particularly, in this example, the minimum value should not fall below the aforementioned low potential on a selected conductor and the maximum value should not exceed the fixed direct potential on the unselected conductors. Under these conditions, rectifiers 40 and 58 are rendered conductive, and the cell defined by conductors '64 and 42 will lurninesce, the light output being determined by the resultant applied voltage which is equal to the algebraic dilference between the instantaneous amplitudes of the two signals.

All other diodes are back biased and non-conductive. Hence, the modulating signals are supplied only to the conditioned cell.

By suitably adjusting the recurrence frequencies of the horizontal and vertical control pulses to both arrays, each cell associated with one horizontal conductor can, in turn, be conditioned for operation before the cells in the ad acent horizontal conductor are so conditioned thus producing a switching and modulating efiect analogous to cathode ray tube scanning.

Tubes 26 and 48 are of known type, as for example that commercially designated as Burroughs type 6700 and identifiedcommercially as a magnetron beam switching tube.

Referring now to Fig.4, there is shown a crossed grid structure of the type shown in Fig. l.

Each of horizontal conductors 42, 44 and 46 is coupled through a corresponding one of rectifiers 136, 138

and 140 to-a first terminal 22. 'Each of the vertical conductors is coupled through a corresponding one of rectifiers 158, 160 and 162m a second terminal 24. All rectifiers are poled in the same sense.

A first switching tube 126 contains, within a gas filled envelope, a plurality of cathodes 130, 132 and 134, an anode 128, and switching electrodes 70 and 72. Cathodes. 130, 132 and 13.4 are each grounded through a cathode resistor, and in addition, each of these cathodes 130, 132 and 134 is coupled to a corresponding one of horizontal conductors 46, 44 and 42. Anode 128 is coupled through a resistor to a point of fixed positive potential.

Similarly, a second switching tube 148 contains, within a gas filled envelope, a plurality of cathodes 152,154 and 156, switching electrodes 74 and 7 6, and an anode 150. Cathodes 152, 154 and'156 are each grounded through a cathode resistor, and in addition, each of these cathodes 15-2, 154 and 156 is coupled to a corresponding one of vertical conductors 64, 66 and 68'. Anode 150 is coupled to a point of fixed positive potential.

The switching electrodes of the tube of Fig. 4 have the same function as the switching electrodes of Fig. l and are energized in the same manner.

Initially a conductive path is established between cathode and anode 128 of tube 126. Similarly, a conductive path is established between cathode 152 and anode 150 of tube 148. Cathodes 152 and 130 are then at. a relatively high potential while the other cathodes of both tubes, cathodes 132, 134, 154 and 156 are grounded. The conductive path in each tube can be switched from cathode to cathode in the same manner as in Fig. 1.

As a result at any one instant, a selected vertical conductor, as for example 64, and a selected horizontal conductor, as for example 42, will be at a relatively high potential, while all other conductors are at substantially ground potential. The cell defined by these selected conductors is then conditioned for operation.

As in Fig. l, a first amplitude modulated signal is applied between terminals 22 and 20, while a second signal opposed in phase to the first signal but otherwise identical thereto is applied between terminals 24 and 20. The amplitude of both signals can vary in any manner desired as long as the extreme values fall within fixed limits as indicated previously. More particularly, in this example the minimum value should not fall below the approximate ground potential of the unselected conductors, and the maximum value should be no greater than the relatively high potential on the selected conductors. Under these conditions, rectifier and 158 are rendered conductive, and the cell defined by conductors 64 and 42 will luminesce, the light output being determined by the resultant applied voltage which is equal to the algebraic difference between the instantaneous amplitudes of the two signals.

All other diodes are back biased and nonconductive. (Note that the rectifiers of Fig. 4 are poled in reverse sense to those of Fig. 1.) Hence, the modulating signals are supplied only to the conditioned cell.

Tubes 126 and 148 are of known type as, for example, that commercially designated by Sylvania Electric Products Inc. as type 6910 and identified commercially as a decade counter- As shown in Fig. 5, both types of tubes 26, 48 and: 126, '148 can be used in a common circuit. In this situation,

however, terminals 22 and-24of Figs. 1 and 4 are tied together as a single terminal 22,. and the rectifiers coupled to the output electrode of one tube have reversed polarity as'compared to the rectifiers coupled to the electrodes of the other tube. A single input-signal is applied between terminals 22 and 20. Theuse of the difierent types of tubes, however, produces a phase reversal of the signal applied to any selected horizontal conductor as compared to the signal applied to any selected vertical conductonso that the modulation action proceeds in effectively the same manner as before.

While I have shown and pointed out my invention as 1 applied above, it will be apparent to those skilled in the art that many modifications can be made within the scope and sphere of my invention.

What is claimed is:

1. In combination with a crossed-gridstructure provided with first and second arrays of parallel separate electrical conductors, the conductors in said first and second arrays extending in difierent non-parallel directions, and an electroluminescent layer interposed and electrically coupled between the first and second array conductors; first and second switching tubes, each tube having a plurality of output electrodes, the output electrodes of said first and second tubes being respectively coupled to a corresponding conductor in a corresponding one of said first and second arrays, each tube further having an input electrode, the input electrodes of both tubes being coupled together; and first and second sets of rectifiers, each first set rectifier being coupled between a first common terminal and a corresponding output electrode of said first tube, each second set rectifier being coupled between a second common terminal and a corresponding output electrode of said second tube.

2. In combination with a crossed-grid structure pro vided with first and second arrays of parallel separate electrical conductors, the conductors in said first and second arrays extending in difierent non-parallel directions, and an electroluminescent layer interposed and electrically coupled between the first and second array conductors; first and second switching tubes, each tube having a plurality of output electrodes, the output electrodes of said first and second tubes being respectively coupled to a corresponding conductor in a corresponding one of said first and second arrays, each tube further having an input electrode, the input electrodes of both tubes being coupled together; and first and second sets of rectifiers, each first set rectifier being coupled between a first common terminal and a corresponding output electrode of said first tube, each second set rectifier being coupled between a second common terminal and a corresponding output electrode of said second tube, all rectifiers being poled in the same sense.

3. The combination as set forth in claim 2, wherein said output electrodes are anodes and said input electrodes are cathodes.

4. The combination as set forth in claim 2, wherein said output electrodes are cathodes and said input electrodes are anodes.

5. In combination with a crossed-grid structure pro vided with first and second arrays of parallel separate electrical conductors, the conductors in said first and second arrays extending in different non-parallel directions, and an electroluminescent layer interposed and electrically-coupled between the first and second array conductors; first and second switching tubes, each tube having a plurality of output electrodes, the output electrodes of said first and second tubes being respectively coupled to a corresponding conductor in a corresponding one of said first and second arrays, each tube further hav ing an input electrode, the input electrodes of both tubes being coupled together, the output electrodes of said first and second tubes being anodes and cathodes respectively, the input electrodes of said first and second tubes being a cathode and an anode respectively; and first and second sets .of rectifiers, each first set rectifier being coupled between a first common terminal and a corref sponding output electrode of said first tube, each second set rectifier being coupled between said first common terminal and a corresponding output electrode of said second tube, the rectifiers in said first set being poled in the same sense, the rectifiersin said second set being poled in reverse sense to the rectifiers of said first set.

' 6. In combination with a crossed-grid structure pro vided with first and second arrays of parallel separate electrical conductors, the conductors in said first array being orientated atan angle with-respect to the conductors in said second array, and an electroluminescent layer interposed and electrically coupled between said first and second array conductors; a commutator for applying a first direct potential, to a selected conductor in each array while applying a second direct potential to the unselected conductors of both arrays; and first and second sets of rectifiers, each rectifier in said first set being coupled between a first common terminal and a difierent corresponding first array conductor, each rectifier in said second set being coupled between a second common terminal and a diiferent corresponding second array conductor, all rectifiers being poled in the same sense; and means to apply first and second alternating signals opposed in phase but otherwise identical to said first and second terminal respectively, said signals having varying amplitudes, the extreme amplitude values falling intermediate said first and second potentials.

7. In combination with a crossed-grid structure pro vided with first and second arrays of parallel separate electrical conductors, the conductors in said first and second arrays extending in ditferent non-parallel directions, and an electroluminescent layer interposed and electrically coupled between the first and second array conductors; commutator means to maintain a selected conductor of each array at a first potential while maintaining all unselected conductors at a second potential, said means including first and second switching tubes, each tube having a plurality of output electrodes, the output electrodes of said first and second tubes being respectively coupled to a corresponding conductor in a corresponding one of said first and second arrays, each tube furtherhaving an input electrode, the input elec trodes of both tubes being coupled together to a first terminal; first and second set of rectifiers, each first set of rectifiers being coupled between a second common terminal and a corresponding output electrode of said first tube, each second set rectifier being coupled between a third common terminal and a corresponding output electrode of said second tube; and means coupled between said first, second and third terminals to apply a first alternating signal between said first and second terminal and to apply a second signal opposed in phase to said first signal but otherwise identical thereto between said first and third terminals, both signals having amplitudes varying between extreme values which approach said first and second potentials as limiting value.

8. In combination with a crossed-grid structure provided with first and second arrays of parallel separate electrical conductors, the conductors in said first and second arrays extending in different non-parallel directions, and an electroluminescent layer interposed and electrically coupled between the first and second array conductors; first and second switching tubes, each tube having a plurality of output electrodes, the output electrodes of said first and second tubes being respectively coupled to a corresponding conductor in a corresponding one of said first and second arrays, each tube further having an input electrode, the input electrodes of both tubes being coupled together to a first terminal; first and second sets of rectifiers, each first set of rectifiers being coupled between a second common terminal and a corresponding output electrode of said first tube, each second set rectifier being coupled between a third common terminal and a corresponding output electrode of said second tube; means coupled between-the output and inputelectrodes at each tube to establish a first conducting path'between the-first tube input electrode and a selected first tube output electrode and to establish a second conducting path between the second tube input electrode and a selected second tube output electrode whereby the potentials on both selected output electrodes attain substantially'the same first value and the potentials on all unselected outputelectrodes attain substantially the same second value; and means to apply a first attenuating signal between said first and second terminals and to apply a second signal between'sa-id first and third terminals, said signals varying in amplitude within a range which cannot exceed that defined by the difference between said first '15 and second potential values whereby the rcctifiers coupleww the selected output electrodes of both tubes are rendered conductive and all other rectifiers are nonconductive. V

References Cited in the file of this patent UNITED STATES PATENTS 1,779,748 Nicholson Oct. 28, 2,313,286 v Okolicsanyi Mar. 9, 1943 2,575,370 Townsend Nov. 20, 1951 2,698,915 Piper Jan. 4, 1955 2,774,813 Livingston Dec. 18, 1956 2,810,099 Townsend et al. Oct. 15, 1957 2,818,531 Peek Dec. 31, 1957 FOREIGN PATENTS Great Britain June 20, 

